Double-Shell Microcapsules Containing Oxidizer for Controlled Gel Breaking

Abstract The development of microencapsulated persulfates represents a significant advancement in hydraulic fracturing operations, particularly for high-temperature reservoirs where controlled gel-breaking is essential. This study demonstrates an innovative encapsulation technique utilizing Acrylonitrile-Butadiene Styrene (ABS) polymer through polydimethylsiloxane (PDMS) induced coacervation and microfluidics approach to effectively encapsulate ammonium persulfate (APS) breakers. Our comprehensive investigation examined multiple characteristics of the fabricated microcapsules, including their chemical design, active agent concentration, physical form, architectural design, controlled-release behavior, and fracturing fluid degradation efficiency. The findings reveal successful formation of micro-scale encapsulated particles featuring permeable exteriors and distinct core-shell configurations. The release kinetics were notably dependent on the proportion between the APS core and ABS shell components during synthesis. This breakthrough technology provides precise control over gel-breaking timing while preventing premature viscosity reduction - a common challenge in high-temperature fracturing operations. The ABS coacervation method proves to be a practical solution for creating temperature-resistant encapsulated breakers with adjustable release profiles. This approach significantly enhances operational efficiency by maintaining optimal fluid viscosity during critical phases of fracturing while ensuring complete gel degradation when required. The technology offers substantial improvements over conventional breaker systems, particularly in challenging high-temperature reservoir conditions where precise control over fluid properties is paramount for successful stimulation operations.